1. Field of the Invention
The present invention relates to a method of manufacturing a support body made of ceramic whereon a semiconductor element, particularly a semiconductor light emitting element can be mounted, and to a semiconductor device that employs the support body made of ceramic.
2. Description of the Related Art
A support body made of ceramic for mounting a semiconductor element has been manufactured by stacking ceramic layers that have not yet been fired, called ceramic green sheets, forming through holes in this stack, making electrical wiring to connect the semiconductor element, and firing the stack. At a time when the ceramic green sheets have been stacked, cleaving lines are drawn so the stack of ceramic green sheets that has been fired can be cleaved by applying a force in a particular direction and separated into individual ceramic packages (refer, for example, to Patent Document 1).
The support body made of ceramic is superior in terms of heat dissipation and heat resistance than packages made of plastic, and enables to be made a light emitting device capable of emitting light of high luminance over a long period of time when a semiconductor light emitting element is mounted thereon. This makes it possible to use the light emitting device as alight source of backlight for a liquid crystal display, and demands are increasing for thinner and smaller light emitting devices. One of such light emitting devices that satisfy this demand is a sideways emission type light emitting device (refer, for example, to Patent Document 2). The sideways emission type light emitting device is mounted and connected to a substrate having an electrically conductive wiring pattern by soldering, after undergoing a process called reflow, so that light is emitted along an optical axis substantially parallel to a mounting surface thereof.
[Patent Document 1]
Japanese Unexamined Patent Publication (Kokai) No. 52-58468
[Patent Document 2]
Japanese Unexamined Patent Publication (Kokai) No. 2003-168824
However, since a support body made of ceramic used in the sideways emission type light emitting device described above is made by firing a stack of ceramic green sheets in mass production, a cleavage surface of this ceramic stack formed when separating it into individual support bodies made of ceramic must be used as a mounting surface for the light emitting device. This results in problems including the following major ones: (1) burrs and/or chippings are caused when cleaving the stack into individual support bodies; (2) cleavage surfaces cannot be made invariably smooth because burrs and chippings generated in a cleavage surface differ from chip to chip; and (3) an angle between the cleavage surface and a light emitting surface differ from chip to chip. The cleavage surface having such problems as described above causes variability in optical characteristics of the device when the light emitting device is mounted on a circuit board to make an optical device.
The support body made of ceramic used to make the sideways emission type light emitting device as described above has electrical wiring formed on a mounting surface thereof adjacent to the a emitting surface. Moreover, the electrical wiring is connected to an electrical circuit formed on an external circuit board by soldering, so as to provide mechanical and electrical connection between the light emitting device and the external circuit board. However, there occur such problems as a part of the light emitting surface is covered by solder during a reflow process and/or short-circuiting occurs as solder lines, which should be separated as positive and negative polarities in a circuit, are brought into contact with each other, thus making it impossible to make light emitting devices of high reliability. When a quantity of solder used is decreased, sufficient electrical and mechanical connection may not be achieved between the light emitting device and an external circuit board. A possibility that the problems described above occur becomes higher when the support body is made of ceramic than when it is made of plastic, and higher when the support body is smaller.